Field of the Invention
The present invention concerns a method for reducing an eddy current field in magnetic resonance tomography. The present invention further concerns a magnetic resonance apparatus that is designed to implement such a method.
Description of the Prior Art
In magnetic resonance tomography, magnetic field gradients generated by gradient coils are used for spatially encoding the magnetic resonance signals. The magnetic field gradients will switch on and off within milliseconds, which is why, due to induction, eddy currents are formed on the conductive structures surrounding the gradient coils. The eddy currents in turn magnetically generate eddy current fields that impair the resulting images in magnetic resonance tomography and reduce the quality thereof. A key factor in the generation of eddy current fields is due to structures in the magnetic resonance device that have a high electrical conductivity. Depending on the design of the magnetic resonance scanner, such a structure can be, for example, the cryostat of the magnet that generates the basic magnetic field.
It is known that eddy current fields will occur, and so the eddy current fields are analyzed and determined during the development and installation of the magnetic resonance apparatus, for example. The results that are obtained can be the basis for determining opposing fields to compensate for the eddy current fields that can be generated by the magnetic resonance scanner by time-dynamic control of gradient coils during a scan.